Electric drive mower with motor generator set

ABSTRACT

Provided is an electric drive riding greens mower. The mower includes a frame which is supported for movement upon a plurality of ground engaging wheels and upon which are supported a motor generator set and a plurality of reel lawn mowers. An electric motor provides driving torque to enable movement of the mower between and over golf course greens or other surfaces to be mowed, electric motors provide driving torque for each of the reel lawn mowers. The motor generator set provides electrical energy for driving the electric motors, including the primary mover and the electrical motors for the reel type lawn mowers. The motor generator set includes an internal combustion motor which provides the mechanical energy to an electric generator which provides electrical energy in response to the received mechanical energy. Further, the mower may include a hydraulic system for operation of reel lift assemblies and the steering mechanism. Hydraulic pressure is supplied by a hydraulic pump powered by one of an electrical motor receiving electrical energy from the generator or directly from the internal combustion engine. The hydraulic motor outputs hydraulic fluid at a pressure sufficient to operate the reel lift and steering mechanisms. Further, the frame member includes a housing which encloses devices which generally operate at substantial noise levels. The housing includes interior and exterior linings which provide passive noise abatement. Within the housing, an active noise abatement system detects and determines ambient noise within the housing and generates output signals which effectively cancel the noise generated within the housing. Such noise abatement assists in providing quiet operation of the mower.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to electrically-driven ridingmowers for use on golf courses and other large grounds, and moreparticularly relates to electrically-driven riding mowers which utilizea bank of batteries for electrical power and, in addition, have analternative source of electrical power such as a motor-generator set oranother bank of batteries.

2. Discussion

The assignee of the present invention recently introduced anall-electric riding greens mower. The mower of this all-electric ridinggreens mower is described in detail in commonly-assigned co-pending U.S.patent application Ser. No. 08/191,553, filed Feb. 3, 1994, now U.S.Pat. No. 5,406,778, issued Apr. 18, 1995, the disclosure of which ishereby incorporated by reference. The triplex riding mower disclosed inthis co-pending application has a bank of batteries supported near therear of the frame of the riding mower which provides electrical powerfor operating the main drive electric motor, three reel motors, andthree lift motors for raising and lowering the reel type mowing heads asneeded. The main motor drives a transaxle that provides a driving forceto the two forward wheels of the triplex mower. The three reel mowerseach directly drive one of the reels, which may be operatedindependently. The three lift motors individually drive a screw-typelift mechanism which raises and lowers a head much the same way thatconventional hydraulically-powered single-rod cylinders do. The mowerincludes a foot pedal controlled by the operator which actuates apotentiometer which directs forward or reverse motion of the vehicle atany desired rate of speed, within the limits permitted by the drivemotor control circuitry and by the power capabilities of the main motorand batteries. Heavy duty contactors switchably apply electrical energyto the reel motors, which are provided with the full voltage of thebattery pack, which is nominally 48 volts obtained by eight 6-voltbatteries wired in series.

There are numerous advantages to using an all-electric riding greensmower. These include very quiet operation, because there is no noisyinternal combustion engine. Another advantage is the absence ofhydraulic devices and accompanying hydraulic oil on the machine, whicheliminates the possibility of hydraulic oil leaks. As is known,hydraulic oil leaks in conventional hydraulically-driven andhydraulically-powered turf care equipment can significantly damage agolf green or fairway if undetected by the mower operator.

Another major advantage of the all-electric greens mower is that it doesnot produce byproducts of combustion, and thus can operate in areaswhere the use of conventional internal combustion powered mowers isprohibited due to pollution concerns and regulations.

While the disclosed all-electric greens mower is quite satisfactory andmuch appreciated, it is difficult and impractical to mow large areas,such as fairways or parks with that style of mower, even whenappropriate reel-style mowing heads are installed. The range of thebattery packs carried by the present mowers remain inherently limited bythe power capabilities of conventional batteries.

One challenge presently faced by many golf course operators is thatmunicipalities and communities, especially those which have residentialhomes bordering the golf courses, restrict by ordinance the hours duringwhich the fairways and greens may be mowed. Homeowners have tired ofnoisy mowing equipment awakening them during the early morning hours,between 5:00 a.m. and 8:00 a.m., and disturbing them in their leisureduring the later evening hours, between 7:00 p.m. and 10:00 p.m., whenthey expect peace and quiet in their neighborhoods. Golf courseoperators, on the other hand, dislike mowing their courses during peakgolfing times, between 7:00 a.m. and 7:00 p.m. during the golfingseason. This challenge presents particular difficulties for golf courseowners whose courses are continuously busy, and usually have a waitinglist of people seeking tee times.

A sufficiently quiet mower, such as an all-electric mower would allowfor mowing fairways and greens on golf courses even where communitieshave instituted noise-limiting ordinances. This is because theall-electric mowers are very quiet. Unfortunately, the battery range ofa riding electric mower with one bank of batteries (even though thebattery weight is in excess of 400 pounds) is limited. Battery-poweredcommercial mowers, therefore, remain impractical for mowing large areasdue to the typically extensive recharge times required to fully rechargethe battery and the undesirable need to interrupt the mowing process(which the golfers wish to have completed as expeditiously as possible)while the batteries are re-charging.

Therefore, it is a principal object of the present invention to providean electrically-operated riding mower capable of mowing large areas ofturf, such as golf course fairways, soccer fields, parks, and municipalgrounds while producing very little noise and minimizing mowinginterruptions to re-charge the on-board batteries. A related object isto provide an all-electric riding mower which is capable of being usedto mow large areas.

Yet another object of the present invention is to provide anelectrically-driven mower which utilizes a motor generator as anelectrical energy source which operates in a quiet, highly efficientmanner in order to conserve fuel and variably deliver electricity on ademand basis to the electrically-driven mower.

Yet another object is to provide a comparatively lightweight electricmower powered by a motor-generator set. A further object is to provide ahybrid fairway mower which utilizes electric motors for the main driveand the reel-style mower heads, while using electro-hydraulic power forthe mower head lift mechanisms and steering.

Yet another object is to provide an extremely quiet, long-lifemotor-generator set arrangement adapted for use on a fairway mower.

Yet another object is to provide an advanced microcomputer-controlledsystem for efficiently operating a motor-generator set even when mowingor traveling at different ground speeds.

Yet another object is to provide a microcontroller-based electroniccontrol system for operating electrically-driven riding mowers withmultiple-mowing heads.

Yet another object is to provide an electrically-driven mower whichconserves the amount of fuel required to operate motor-generator set byoperating the motor-generator at substantially peak efficiency at alltimes.

Still further objects of the present invention are set forth in and willbecome apparent from the following summary of the invention and thedetailed description and claims thereafter.

SUMMARY OF THE INVENTION

In light of the foregoing problems and in order to fulfill one or moreof the foregoing objects, there is provided, in accordance with a firstaspect of the present invention, a self-propelled riding mower having aframe supported on a plurality of ground engaging wheels. The framesupports a means for mechanically generating electrical energy andfurther supports a plurality of reel type lawn mowers which are movablebetween a raised position and a lowered position, in accordance withoperation and non-operation, respectively. The reel mowers are driven byelectrical motors which receive electrical power from the means formechanically generating electrical energy. A prime mover having anelectric motor is also supplied with electric energy from the means forgenerating electrical energy, where the prime mover is also adapted toprovide torque to one of the ground engaging wheels upon which the frameis supported.

In accordance with a second aspect of the present invention, aself-propelled riding mower includes a frame supported on a plurality ofground engaging wheels. The self-propelled riding mower also includes aninternal combustion motor and a device for generating electrical energyin response to mechanical motion provided by the internal combustionmotor. A plurality of reel type law mowers are also supported from theframe and are driven by electric motors which receive electrical powerfrom the device for generating electrical energy. Further, a prime moveris adapted to provide driving torque to at least one of the groundengaging wheels and includes an electric motor supplied with electricalenergy from the device for generating electrical energy.

In accordance with another aspect of the present invention, a motorgenerator set which provides electrical energy for operating aself-propelled riding mower. An internal combustion motor and agenerator make up the motor generator set, and the generator provideselectrical energy in response to mechanical input from the internalcombustion motor. The generator provides electrical energy for drivingat least one electric motor. The electric motor may be connected to acorresponding reel type lawn mower supported from the riding mower. Avoltage regulator modulates the electrical output of the generatorwithin a predetermined range to ensure proper operation of theself-propelled riding mower.

In accordance with yet another aspect of the present invention, aself-propelled riding mower includes a frame supported on a plurality ofground engaging wheels. The mower includes a device for mechanicallygenerating electrical energy and hydraulic pressure generator forreceiving hydraulic fluid at an input pressure and providing hydraulicfluid at an output pressure. A drive apparatus powered by the device formechanically generating electrical energy provides mechanical input tothe hydraulic pressure generator. Further, a plurality of reel type lawnmowers are supported from the frame and are moveable between a raisednon-operative position and a lowered operative position in which thereel type lawn mowers engage the ground. The plurality of reel type lawnmowers are driven by electric motors which receive electrical power fromthe device for generating electrical energy.

In accordance with yet another aspect of the present invention, aself-propelled riding mower includes a frame supported upon a pluralityof ground engaging wheels. An internal combustion motor is mechanicallyconnected to a device for generating electrical energy in response tomechanical motion, where the internal combustion motor impartsmechanical motion in order to generate electrical energy. A housingencloses the internal combustion engine and the device for generatingelectrical energy. Further, the housing includes noise abatement forreducing noise generated within the interior of the housing, therebyreducing noise reaching the exterior of the housing.

In accordance with yet another aspect of the present invention, aself-propelled mower includes a frame supported on a plurality of groundengaging wheels and a motor generator set for generating electricalenergy in response to mechanical motion. A housing encloses the motorgenerator set and includes noise abatement for reducing noise generatedwithin the interior of the housing. The noise abatement includes passivenoise abatement implemented as interior and exterior linings of thehousing. The self-propelled mower also includes active noise abatementin which an acoustical sensor detects acoustical sound generated withinthe interior of the housing and outputs a signal varying in accordancewith the detected sound. An electronic controller receives as input thesignal from the acoustical sensor and determines an output signal whichwill cancel the noise associated with the input signal. The outputsignal is input to a speaker which thereby produces the acousticaloutput to substantially cancel the sound detected by the acousticalsensor.

These and other objects, advantages and aspects of the present inventionmay be further understood by referring to the detailed description,accompanying Figures, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings form an integral part of the description of the preferredembodiments and are to be read in conjunction therewith. Like referencenumerals designate the same or similar components or features in thevarious figures, where:

FIG. 1 shows a perspective view of an electrically-driven riding mowerof the present invention which has three wheels supporting the frame towhich are mounted three mowing heads and lift mechanisms as well as anelectric-drive motor and battery pack;

FIG. 2 shows a top view of five-gang riding mower powered by an on-boardbattery pack and a motor generator set;

FIG. 3a is a block diagram for an electrically-driven mower which usesan DC drive motor;

FIG. 3b is a block diagram for an electrically-driven mower which uses aAC drive motor;

FIG. 3c is a block diagram of a dual motor, gear wheel direct drivesystem to individually power the drive wheels of the turf mower;

FIG. 3d is a block diagram of a dual motor chain drive system toindividually power the drive wheels of the mower;

FIG. 4 shows a top view of the FIG. 1 mower adapted to include ahydraulic system to provide drive to at least one of the lift mechanismand the steering mechanisms;

FIG. 5 shows a perspective view of a five-gang riding mower powered byan on-board battery pack and motor generator set combination to powerelectric and hydraulic drive systems to operate the mower;

FIGS. 6a and 6b show a detailed block diagram showing a preferred motorgenerator set arrangement having two types of sound abatement, and ahydraulic steering system connected through an electric clutch;

FIG. 7 shows a detailed block diagram showing a preferred motorgenerator set arrangement to provide electrical energy for driving ahydraulic pump motor and also having active noise cancellation for themotor generator set;

FIG. 8 shows a detailed block diagram showing a preferred motorgenerator set arrangement which provides mechanical energy for drivingthe hydraulic pump mower and which includes active noise cancellation tolimit noise output by the motor generator set and the hydraulic pump;and

FIG. 9 is a detailed block diagram of an electronic control system ofthe present invention which uses a microprocessor based controller tomodulate the power output of the motor generator set, actuate theelectric devices, and direct fly-by-wire electric steering through anelectric motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a riding greens mower powereddirectly by electric power or indirectly by electric power through ahydraulic drive system. For the purpose of providing a detaileddescription of the preferred embodiments of the invention, the inventionis described as embodied as an electric (or electrohydraulic) triplexgreens reel mower or a quintplex greens reel mower, each having a framesupported on at least three wheels and the defined number of reel typelawn mowers supported from the frame member, an operator stationincluding a seat from which an operator controls the function of themower, and an on-board source of electrical energy, such as batteriesand/or a motor generator set. It should be readily understood that theteachings of the present invention are not limited to the specific typeof mowers described herein and can be extended to a variety ofapplications in the turf care industry and elsewhere.

FIG. 1 illustrates a general arrangement of the electric turf mower 10with a motor generator set. Mower 10 includes a frame 12 supported formovement on forward drive wheels 14 and steerable rear wheel 16. Threereel lawn mowers 18a and 18b (the third mower not shown) are supportedfrom frame 12 by reel lift assemblies (not shown in FIG. 1). Reel lawnmower 18a is disposed at the right forward comer of frame 12, and reellawn mower 18b is substantially disposed below frame 12. Thisarrangement assures that the mowers precede the ground engaging wheelssuch that the turf (particularly on a golf green) is mowed prior tobeing traversed by the ground engaging wheels, thereby ensuring aprecise and consistent length of cut.

Each of the reel lawn mowers are driven by an electric reel motor 22,which is supplied with electrical energy from on-board battery powersource 24. Battery power source 24 preferably provides between 12 voltsto 96 volts of electrical energy. In the preferred embodiment, batterypower source 24 includes eight six-volt lead-acid batteries 26 connectedin series to provide 48 volts of electrical energy. As will beappreciated, lower battery voltages may be used with smaller units whilehigher battery voltage may be used with larger units, such as the fivegang fairway mower described with respect to FIG. 2. Battery powersource 24 is rechargeable and it should be readily understood that anytype of batteries, such as the above-mentioned lead-acid or nickelcadmium (NiCad) batteries may be used with mower 10. Battery powersource 24 also provides electrical energy to a drive motor or primarymover (not shown) which is adapted to provide driving torque through adriving axle (not shown) to each of the forward drive wheels 14 forpropelling mower 10 over the mowing surface.

A motor generator set 28 provides a second source of power to charge thebattery power source 24 and to provide electrical energy for driving themower 10. The motor generator set 28 includes an internal combustionmotor 29 which provides mechanical input to generator 31. The generator31 converts the mechanical energy input from internal combustion motor29 into electrical energy output to the battery power source 24 and tothe electrical components of mower 10. Motor generator set 28 may be anyof a number of typical motor generator sets well known in the art.

Mower 10 is operated from an operator station 30, which includes a seat32 supported above frame 12 and battery power source 24 by seat support34. Operator station 30 also includes a control support arm 36 which issecured to a rearward portion of the frame 12. Control support arm 36extends forwardly and around the seat 32 such that a steering wheel 38is located directly in front of the operator and a control module 40 forhousing control elements such as control switches and indicators iswithin view and reach of the operator. Located on control support arm 36and adjacent to steering wheel 38 may be a communication panel which isoperable for displaying mowing and operating instructions to theoperator. Formed integral to frame 12 and associated with operatorstation 30 is a foot deck 44. Foot deck 44 is ergonomically angled foroperator comfort and ease of reaching the drive pedal 46, brake pedal48, and the reel mower activation switch (not shown in FIG. 1). Seat 32further may also include an assist handle for assisting the operator onand off the mower 10.

Mower 10 also includes a steering mechanism 50 for rotating steerablerear wheel 16 of mower 10. Steerable rear wheel 16 is mounted to a pairof brackets 52 secured to a U-shaped yoke member 54. U-shaped yokemember 54 includes an upper spindle 56 which is journally supportedwithin a sleeve which is in turn secured to frame 12. Spindle 56projects upwardly through frame 12 allowing for a steering sprocket 58to be secured thereto. Steering sprocket 58 has a plurality of teeth 60formed along its circumference for engaging a plurality of complimentaryteeth formed in a shaft 62 projecting from a steering motor 64 securedto the frame 12. Steering motor 64 controls the projection andretraction of shaft 62 which, through engagement of teeth 60 inducesrotation of steering sprocket 58, thereby causes rotation of steerablerear wheel 16. In an alternative configuration steering motor 64 may bea self contained hydraulic cylinder which controls the projection andretraction of shaft 62. The self contained hydraulic cylinder 64includes a hydraulic pump, such as a gear pump, which operates in twodirections to control projection and retraction of the hydrauliccylinder portion of steering motor 64. An electric motor drives thehydraulic pump to modulate the hydraulic fluid pressure and controlextension and retraction of the cylinder. Steering motor 64 typically isan electrically or hydraulically actuated device which receives controlcommands from an electronic (or hydraulic) controller to causeprojection or retraction of shaft 62.

FIG. 2 illustrates a five gang mower 70 which defines a secondembodiment of the present invention and is directed primarily for mowingwider strips of turf than the mower 10 of FIG. 1. An example of such afive gang mower 70 may be found with reference to a typical golf coursefairway mower. Mower 70 includes a frame 72 supported for movement ondrive wheels 74 and steerable rear wheels 76. Five reel type lawn mowers78a, 78b, 78c, 78d, and 78e are supported from frame 72 by reel liftassemblies 80. Three of the reel type lawn mowers 78a, 78b, and 78c aredisposed forward of drive wheels 74, and two reel lawn mowers 18d and18e are disposed between drive wheels 74 and steerable rear wheels 76.This arrangement assures that the mowers precede the drive wheels 74 and76 so that the fairway turf is mowed prior to traversal by the groundengaging wheels, thereby ensuring a more precise and consistent lengthof cut. Each of the reel lawn mowers 78a-e are driven by an electricreel mower motor 82 which is supplied with electrical energy fromon-board battery power source 84. As described above with respect toFIG. 1, battery power source 84 preferably provides between 12 volts and96 volts of electrical energy. In a preferred embodiment, battery powersource 84 includes eight six-volt lead-acid batteries 86 connected inseries to provide 48 volts of electrical force. Such capacity providesthe capability for cutting approximately 2 average golf course fairways,including transportation of mower 10 between the fairways. As describedabove and as will be appreciated, lower battery voltages may be usedwith smaller units while higher battery voltages may be used with largerunits. Battery power source 84 is rechargeable and it should be readilyunderstood that any type of batteries, such as the above-mentionedlead-acid or nickel cadmium (NiCad) batteries may be used with mower 70.

Battery power source 84 also provides electrical energy to a drive motoror primary mover (not shown in FIG. 2) which is adapted to providedriving torque through a driving axle (also not shown in FIG. 2) to eachof drive wheels 74 for propelling mower 70 over the fairway being mowed.The drive motor is capable of providing an average cutting speed formower 70 of approximately 7 miles per hour (MPH) during mowingoperations and approximately 15 MPH during transport.

Mower 70 also includes a motor generator set 90 comprising an internalcombustion (IC) motor 92 for providing mechanical drive to a generator94. Mechanically driving generator 94 produces electrical energy appliedto both battery power source 84 and the drive motor and other electricaldevices in accordance with the electrical power needs of mower 70. Afuel tank 96 stores fuel for driving internal combustion motor 92.

Also as described with respect to the mower 10 of FIG. 1, mower 70 isoperated from an operator station 100 which includes a seat 102supported above frame 72 and battery power source 84 by a seat support(not shown). Operator station 100 also includes a steering wheel 104located directly in front of the operator and a control module (notshown) for housing the control elements, such as control switches andindicators, within the view and reach of the operator. Formed integralto the frame 12 and associated with operator station 100 is a foot deck106. Foot deck 106 is ergonomically angled for operator comfort and easeof reaching the drive pedal 108 and other associated pedals, such as thebrake pedal and mow switch (not shown).

In operation, the motor generator set 28 (and 90) of FIG. 1 (and 2)outputs electrical energy which both charges the battery power sources24 (and 84) and operates the drive motor and other electrical devices.The internal combustion motor 29 (and 92) outputs mechanical energy,typically through an output shaft (not shown) to the generator 31 (and94). The generator 31 (and 94) converts the mechanical energy input frominternal combustion motor 29 (and 92) into electrical energy anddelivers electrical energy at a predetermined frequency or voltage,either of which may vary depending upon the particular configuration ofthe motor generator set.

FIGS. 3a and 3b depict a typical configuration for the electrical drivesystem of the mowers of FIG. 1 (and 2) for operating the main drivemotor. The motor generator configurations of FIGS. 3a and 3b will bedescribed generally with equal reference to FIGS. 1 and 2. One skilledin the art will readily recognize that either configuration may bereadily adapted for operation on either of the mowers in FIGS. 1 and 2.An internal combustion motor 110 provides mechanical energy via anoutput shaft 112 to an alternator 114. The output shaft 112 causesrotation of the rotor (not shown) of the alternator 114, therebyresulting in the alternator 114 producing electrical energy for outputto a voltage regulator 116. In the particular configuration of FIG. 3a,the drive motor is represented as a direct current (DC) motor 118 whichconverts DC voltage into rotational motion applied to an output shaft120. Output shaft 120 is input into a transmission 122 which convertsthe mechanical energy provided by output shaft 120 into torque fordriving the left and right axles 124a and 124b, respectively, to causethe drive wheels 126a and 126b to rotate, respectively. Because motor118 is a DC motor, the combination of alternator 114 and voltageregulator 116 provides a DC voltage signal to DC motor 118. The outputof voltage regulator 116 also is input to a battery pack 127 whichcomprises a plurality of batteries 128 connected in series so that thecombined series connection of the batteries 128 results in an outputvoltage sufficient for operation of DC motor 118.

A motor controller 130 receives the output voltage provided by voltageregulator 116 and battery pack 127 and modulates the voltage input to DCmotor 118. In this manner, motor controller 130 modulates the output ofDC motor 118 by modulating the voltage input to DC motor 118. Motorcontroller 130 operates in conjunction with an electronic controlcircuit 132, which determines the desired mower speed and modulates theoutput of DC motor 118 and outputs a control signal to motor controller130 in order to vary the output of DC motor 118. Electronic controlcircuit 132 receives input signals through a pair of potentiometers 134and 136 which are controlled by operator foot pedals 138 and 140,respectively. When the operator (not shown) presses operator foot pedal138 (the drive pedal), a change in the position of potentiometer 134results in a variation of the signal input to electronic control circuit132. Similarly, when the operator depresses operator foot pedal 140 (thebrake pedal), a change in the position of potentiometer 136 results in avariation of the signal input to electronic control circuit 132.Electronic control circuit 132 determines the desired output of DC motor118 in accordance with the input signals and generates a control signalinput to motor controller 130. Motor controller 130 in turn varies theoutput voltage applied to DC motor 118 in accordance with the receivedcontrol signal.

Electronic control circuit 132 also receives input from operator controlpanel 142, which is analogous to the operator control panels mentionedwith respect to FIGS. 1 and 2. Electronic control circuit 132 thusprovides additional control for other mower control functions. Forexample, electronic control circuit 132 may also include a left motorcontroller 144 and a right motor controller 146 which operate left motor148 and right motor 150, respectively. The electronic control circuit132 receives input from operator control panel 142 and generates controlsignals input to left motor controller 144 and right motor controller146. The respective controllers then generate the desired signals forcarrying out the operations indicated in accordance with input from theoperator control panel 142. Examples of such controlled functionsinclude reel mower positions (raised or lowered) and reel mower speed.Left motor 148 and right motor 150, in addition to receiving controlsignals from left motor controller 144 and right motor controller 146,receive driving electrical energy from a combination of the output ofbattery pack 127 or voltage regulator 116.

It will be understood by those skilled in the art that variousmodifications of FIG. 3a may result in various alternative controlsystems. For example, if voltage regulator 116 is a variable voltageregulator, electronic control circuit 132 could alternatively provide acontrol signal directly to voltage regulator 116. Voltage regulator 116could then output a driving voltage directly to DC motor 118, therebyeliminating the need for motor controller 130. Voltage regulator 116could additionally provide a separate charging voltage directly tobattery pack 127 as well.

FIG. 3b depicts an alternative configuration for providing drivingenergy to the primary mover of the mowers of FIGS. 1 and 2. Likecomponents of FIGS. 3a and 3b have been described with respect to FIG.3a and will not be described with respect to FIG. 3b. In thisalternative configuration, an AC motor 158, rather than a DC motor,functions as the primary mower. In operation, the electrical powersystem of FIG. 3b operates similarly to that described in FIG. 3a. Theoutput from voltage regulator 116 remains a DC voltage which providescharging electrical energy to battery pack 127. Voltage regulator 116also outputs a DC voltage to inverter 156. Inverter 156 converts the DCvoltage signal to an AC voltage signal which is applied to AC motor 158.AC motor 158 is powered by an AC signal and provides a driving torque tooutput shaft 120.

In yet another embodiment for providing driving torque to the drivewheels 126a and 126b, FIG. 3c depicts a dual motor drive system forproviding torque to the drive wheels 126a and 126b. Motor controller 160receives electrical power supplied by the combined motor generator setand battery packs as described with respect to FIGS. 3a and 3b,depending upon the particular configuration of the drive motor. Motorcontroller 160 also receives a signal from electronic control circuitfor directing the output of motor controller 160. Motor controller 160provides electrical control signals to each of a right drive motor 162aand a left drive motor 162b. Each control signal output to therespective motors 162a and 162b directs operation of that particularmotor. The motors 162a and 162b each provide a driving output to gearreducers 164a and 164b, respectively. The gear reducer sets 164a and164b reduce the rotational speed of the motors 162a and 162brespectively, from a relatively high revolution per minute (RPM) rate toa substantially lower RPM rate suitable for the drive wheels 126a and126b. Thus, each drive wheel 126a and 126b is individually driven by therespective gear motor arrangements provided by the motor 162 and gearreducer 164.

The motor and associated gear reducer 162a and 164a for the right drivewheel and 162b and 164b for the left drive wheel may be combined into asingle integrated unit 161a and 161b. The integrated gear wheels motors161a and 161b may also form an axle which attaches to the frame (12 ofFIG. 1) at one end and the wheel hub via an output shaft 163a and 163bat the other end. This configuration thus provides an integral wheel hubwhich attaches directly to the vehicle frame and supports the vehicleframe above the drive wheels 126a and 126b.

FIG. 3d depicts yet another configuration for dual motor drive systemwhich employ a gear wheel motor configuration. Note that like elementsfrom FIG. 3c will be similarly referenced in FIG. 3d and the descriptionof FIG. 3 applies equally to said same elements of FIG. 3d. Thus, themotor controller 160 receives both driving electrical signals andcontrol signals from the motor generator set/battery pack combinationand the electronic control circuit, respectively. The motor controller160 outputs control signals to right drive motor 162a and left drivemotor 162b. Right drive motor 162a and left drive motor 162b in turnprovide driving torque to gear reducer sets 164a and 164b, respectively.In the embodiment of FIG. 3d, the gear reducer sets 164a and 164bprovide torque to chain drive systems 166a and 166b. Chain drives 166aand 166b typically include input sprockets driven by gear reducer sets164a and 164b and also include output sprockets which typically rotatesin association with each of drive wheels 126a and 126b, respectively.Thus, in operation, motor controller 160 provides control signals toeach of drive motors 162a and 162b. Drive motors 162a and 162b provideoutput torque to gear reduction sets 164a and 164b, respectively. Thegear reducer sets 164a and 164b in turn provide output torque to chaindrives 166a and 166b, which imparts rotational motion to drive wheels126a and 126b, respectively. In an alternative embodiment, the drivemotors 162 and gear reducer sets 164 may be combined into an integraldrive motor and gear reducer system 165a and 165b. In a furthervariation, the chain drive systems 166a and 166b may be configured toprovide a gear ratio which eliminates the need for gear reducing sets164a and 164b. Further, the motors in the gear reducer systems describedabove preferably output 4 to 6 kilowatts of power, and the desired gearratio varies, but is preferably in the range of 6:1 to 18:1.

In an alternative configuration to the triplex gang mower 10 shown inFIG. 1, FIG. 4 depicts a triplex electrohydraulic mower 170 in which,the reel motors, the lift mechanisms and the steering system arehydraulically operated by a hydraulic system. The hydraulic systemincludes an electrically or mechanically driven pump which may be drivenby an electric motor powered by either of the battery pack or the motorgenerator set. In the alternative, the hydraulic pump may bemechanically driven by the internal combustion motor of themotor-generator in a direct drive configuration.

The triplex, gang electrohydraulic mower 170 includes a frame 172supported for movement on forward drive wheels 174 and steerable rearwheel 176. Three reel type lawn mowers 178a, 178b, (and a third reeltype mower not shown, but disposed beneath the frame) are supported fromthe frame 172 by reel lift assemblies 180a and 180b, respectively. Reellawn mower 178a is disposed at the right forward corner of frame 172,and reel lawn mower 178b is disposed at the left front corner of frame172. The third reel lawn mower is essentially disposed below frame 172.As described with respect to FIG. 1, this arrangement ensures that themowers precede the ground engaging wheels such that the turf is mowedprior to being traversed by the ground engaging wheels, thereby ensuringa precise and consistent length of cut. Each of the reel lawn mowers aredriven by a hydraulic (or optionally an electric) reel motor 182a, 182b,(and a third motor not shown), respectively.

Hydraulic lines 184 supply hydraulic fluid to the hydraulic reel motors182a and 184b and the lift assembly 180a. A hydraulic pump 186 supplieshydraulic fluid at a pressure via hydraulic lines 184. The hydraulicpump 186 receives hydraulic fluid from a hydraulic fluid tank reservoir190 and applies hydraulic fluid at an output pressure to the motors 182and reel lift assemblies 180a and 180b at a pressure sufficient to drivethe respective devices. Hydraulic pump 186 may be driven by one or acombination of an electric motor or through direct drive from theinternal combustion motor 192 of a motor generator set 194. Liftassembly 180b demonstrates an alternative configuration for the liftassemblies for mower 170 in which a self contained electrohydraulicassembly includes an electric motor, a hydraulic pump, a cylinder, and areservoir and receives electrical control signals to direct the raisingand lowering of reel lawn mower 178b. The assembly operates similarly tothe electrohydraulic steering motor 65 of FIG. 1. A bi-directionalelectric motor 181 drives a bi-directional, hydraulic pump 183, such asa two way gear pump, through a gear reduction set. The hydraulic pump183 receives hydraulic fluid from the reservoir 185 and outputs ahydraulic fluid pressure to displace the hydraulic cylinder 187.Displacement of the hydraulic cylinder raises and lowers reel lawn mower178b. It should be noted that the configuration of reel lift assembly180b may be implemented each of the reel lift assemblies.

In the electric motor arrangement, hydraulic pump 186 may be driven byan electric motor which is supplied with electrical energy from anon-board battery power source 196 or the motor generator set 194.Battery power source 196 preferably provides between 12 volts to 96volts of electrical energy. In a preferred embodiment, battery powersource 196 includes eight six-volt lead-acid batteries 198 connected inseries to provide 48 volts of electrical energy. As will be appreciated,lower battery voltages may be used with smaller units while higherbattery voltages may be used with larger units such as the fairway mowerdescribed with respect to FIG. 5. Battery power source 196 isrechargeable and it should be readily understood that any type ofbatteries, such as the above-mentioned lead-acid or nickel cadmium(NiCad) batteries may be used with electrohydraulic mower 170. Batterypower source 196 also may optionally provide electrical energy to aprimary mower or drive motor (not shown) which is adapted to providedriving torque through a driving axle (not shown) to each of the drivewheels 174 for propelling electrohydraulic mower 170 over the mowingsurface.

Electrohydraulic mower 170 is operated from an operator station 200which includes a seat 202 supported above frame 172 and battery powersource 196 by a seat support (not shown). Operator station 200 alsoincludes a control support arm 204 which is secured to a rearwardportion of the frame 172. Control support arm 204 extends rearwardly andaround the seat 202 such that a steering wheel 206 is located directlyin front of the operator such that a control module 208 for housing thecontrol elements such as control switches and indicators is within viewand reach of the operator. Located on control support arm 204 andadjacent to steering wheel 206 is a communication panel 210. Formedintegral to frame 172 and associated with operator station 200 is a footdeck 212. Foot deck 212 is ergonomically angled for operator comfort andease of reaching the drive pedal 214, brake pedal 216, and the reelmower activation switch 218. Seat 202 also includes an assist handle(not shown) for assisting the operator on and off the mower.Electrohydraulic mower 170 also includes a steering mechanism forrotating steerable rear wheel 176 of electrohydraulic mower 170. Therear wheel steering mechanism operates as described with respect to FIG.1 with the additional feature that the motor 220 which controlsextension and retraction of the shaft 222 is a hydraulically operatedmotor. Motor 220 receives hydraulic fluid at pressure provided byhydraulic pump 186 and operates in two directions so as to causeextension and retraction of shaft 222.

Referring back to the motor generator set 194, the motor generator set194 operates substantially as described with respect to FIG. 1. Motorgenerator set 194 includes an internal combustion motor 192 whichprovides mechanical input to generator 193. The mechanical input togenerator 193 results in the output of electrical energy supplied tobattery power source 196 and supplied to various electric motors,including steering motors, and primary mover motors. Internal combustionmotor 192 also optionally drives hydraulic pump 186 which providesmechanical energy for the pressurization of hydraulic fluid by hydraulicpump 186. Internal combustion motor 192 is powered by a fuel sourcestored in fuel tank 195. The motor generator set 194 may also provideelectrical energy to the primary mower in the same manner as describedwith respect to FIGS. 3a and 3b.

FIG. 5 illustrates a similarly configured apparatus to that of FIG. 4implemented as a five gang electrohydraulic mower 230. Electrohydraulicmower 230 is implemented as a five gang, electrohydraulic mower in whichmechanical energy is derived from a combination of electric drive andhydraulic drive. A battery pack or power source, to be described furtherherein, provides the electrical energy to power the electricallycontrolled devices. Similarly, a hydraulic motor which providespressurized hydraulic fluid to drive the hydraulically actuated devicesmay be driven by one or a combination of an electric motor and aninternal combustion engine of a motor generator set, to be describedfurther herein. The five gang electrohydraulic mower 230 correspondsprimarily to a device for mowing wider strips of turf than the mowerdepicted in FIG. 4. An example of such a five gang mower may be foundwith respect to a typical golf course fairway mower. Electrohydraulicmower 230 includes a frame 232 supported for movement on forward drivewheels 234 and steerable rear wheels 236. Five reel type lawn mowers238a, 238b, 238c, and 238d (shown partially and the fifth reel lawnmower not shown) are supported from frame 232 by reel lift assemblies240a, 240b, 240c and 240d (the fifth reel lift assembly not shown),respectively. In an embodiment depicted in FIG. 5, two of the reel typelawn mowers 238a and 238b are disposed forward of forward drive wheels234, and two reel lawn mowers 238c and 238d are disposed forward ofsteerable rear wheels 236. This arrangement ensures that the mowersproceed the wheels 234 and 236 so that the fairway turf is mowed priorto traversal by the ground engaging wheels. This ensures a more preciseand consistent length of cut.

Each of the reel lawn mowers 238a, 238b, 238c, and 238d are driven byreel mower motors 242a, 242b, 242c, 242d (and a fifth mower motor notshown) respectively. Each of the mower motors 242a, 242b, 242c, and 242dmay be hydraulically powered in a first configuration or electricallypowered in a second configuration. In the hydraulic configuration themotors are driven by hydraulic fluid supplied at pressure via hydrauliclines 244. A hydraulic pump (not shown in FIG. 5, but to be describedfurther herein) provides hydraulic fluid at pressure to each of therespective hydraulic mower motors via hydraulic lines 244. In theelectrically operated configuration, electrical energy drives therespective mower motors which impart mechanical drive to the reelmowers.

A battery power source 246 preferably provides 12 volts to 96 volts ofelectrical energy. In a preferred embodiment, battery power source 246includes eight six-volt lead-acid batteries 248 connected in series toprovide 48 volts of electrical force and further providing a capabilityof cutting approximately two average golf course fairways, includingtransportation of electrohydraulic mower 230 between the fairways. Asdescribed above, as will be appreciated, lower battery voltages may beused with smaller units while higher battery voltages may be used withlarger units. Battery power source 246 is a rechargeable battery powersource, and it will be understood by one skilled in the art that anytype of batteries, such as the above-mentioned lead-acid or nickelcadmium (NiCad) batteries may be used with electrohydraulic mower 70.Battery power source 246 may optionally provide electrical energy todrive an electric motor which functions as a prime mover and an electricmotor which functions as a hydraulic pump to supply fluided pressure fordriving the hydraulically actuated devices.

Electrohydraulic mower 230 also includes a motor generator set 250comprising an internal combustion motor 252 providing mechanical inputto a generator 254. The mechanical input provided by the internalcombustion motor 252 causes generator 254 to output electrical energy.The electrical energy provided by generator 254 may be used to power anyof the electric motors and to charge the battery power source 246.Electrohydraulic mower 230 also includes a housing 256 for housing themotor generator set 250. Housing 256 preferably includes soundinsulation capabilities so as to significantly reduce the soundemanating from the electrohydraulic mower 230. Such sound reductionrenders the electrohydraulic mower 230 particularly attractive for useon golf courses located in and around residential communities. Thereduction in noise significantly reduces the interruptions experiencedby those living on or near the golf course due to the noise of thetypical fairway mower.

Referring to FIG. 5 in conjunction with FIGS. 6aand 6b, theelectrohydraulic control system of electrohydraulic mower 230 will bedescribed. FIGS. 6 a and 6b depict a block diagram of the control systemfor both the combines electronic and hydraulic aspects of the controlsystem. Regarding the electronic control system, electrical energy todrive the electric turf mower is stored in electrical storage batteries248 which are connected in series by a plurality of jumpers to define abattery power source 246. The battery power source 246 of the presentinvention is preferably rechargeable, and motor generator set 250supplies electrical energy sufficient to recharge battery power source246 and operated electrohydraulic mower 230. The motor generator set 250includes an internal combustion motor 252 which provides mechanicaloutput on an output shaft 260 to a generator 254. In the block diagramof FIGS. 6a and 6b, note that generator 254 is depicted as a directcurrent (DC) voltage output device, but may output an alternatingcurrent (AC) signal as well. The internal combustion motor 252 alsoprovides mechanical input through generator 254 to drive a second outputshaft 262 which is attached to a fan 264. Rotation of output shaft 262in turn causes rotation of fan 264 thereby providing an airflow tomaintain a relatively low operating temperature within the housing 256of the electrohydraulic mower 230. Generator 254 outputs a DC voltage tovoltage regulator 266. Voltage regulator 266 modulates the input voltagereceived from generator 254 and outputs a voltage which may be varied inaccordance with a control signal supplied by electronic power governor268. Thus, electronic power governor 268 receives a sample voltage fromvoltage regulator 266 and returns a voltage control signal to voltageregulator 266 to vary the output thereof.

The output from voltage regulator 266 is selectively input to batterypower source 246. Selective output of the voltage from voltage regulator266 to battery power source 246 is controlled through a pair ofcontactors 270 and 272. The contactors 270 and 272 are in turncontrolled by a gen set monitor 274. Gen set monitor 274 is anelectronic control module which monitors the voltage output by voltageregulator 266. Depending on the voltage level output by voltageregulator 266, gen set monitor 274 selectively actuates contactors 270and 272 to enable and disable application of voltage output by voltageregulator 266 to battery power source 246. Gen set monitor 274determines actuation of contactors 270 and 272 in accordance with thevoltage output by voltage regulator 266 and the voltage output ofbattery power source 246. Gen set monitor 274 first determines that theoutput from voltage regulator 266 can sufficiently charge battery powersource 246 prior to actuating contactors 270 and 272. If the voltageoutput from voltage regulator 266 can sufficiently charge battery powersource 246, gen set monitor 274 then determines the output of batterypower source 246. When the output of battery power source 246 dropsbelow a predetermined threshold, gen set monitor 274 actuates contactors270 and 272 to allow application of the output from voltage regulator266 to battery power source 246, thereby charging each of the respectivebatteries 248 of battery power source 246.

Gen set monitor 274 also exchanges control information with interfacemodule (IFM) 276. Interface module 276 provides status information togen set monitor 274, and gen set monitor 274 returns control signals tointerface module 276. Interface module 276 receives control signals fromgen set monitor 274 and outputs the appropriate control signals toengine speed governor (ESG) 278, electronic power governor (EPG) 268,and starter motor (SM) 280. In operation, interface module 276 receivesthe control signal from gen set monitor 274 and generates thecorresponding appropriate control signal for each of electronic powergovernor 268, electronic speed governor 278, and starter motor 280.

With respect to electronic speed governor 278, electronic speed governor278 receives a temperature signal from temperature switch 282 and aspeed signal from speed sensor 284. Speed sensor 284 is anelectromagnetic pickup which gene rates a frequency signal in responseto passage of the individual teeth of wheel 286. The frequency of thesignal output by speed sensor 284 determines the speed of the outputshaft 260 of internal combustion motor 252. Status information relatedto the operation of the electronic speed governor 278 is relayed fromthe electronic speed governor 278 to gen set monitor 274 throughinterface module 276. Gen set monitor 274 then generates the appropriatecontrol signals sent to electronic speed governor 278 thorough interfacemodule 276. In response to the particular control signals, electronicspeed governor 278 outputs control signals to fuel injection system(FIS) 288. Fuel injection system 288 generates the appropriate controlsignals for operating the fuel injectors (or carburetor) of internalcombustion motor 252 to obtain the desired operation of internalcombustion motor 252. The fuel injection system 288 th us varies theoutput speed of internal combustion motor 252.

Similarly, electronic power governor 268 receives voltage levelinformation from voltage regulator 266 and generator output shaftrotational information from speed sensor 290. Speed sensor 290 operatesas described with respect to speed sensor 284 and tooth wheel 286. Speedpickup 290 outputs a signal with a frequency varying in accordance withthe rotational speed of output shaft 262. Speed pickup 290 outputs asignal in response to passage of the individual gear teeth of toothedwheel 292. Electronic power governor 268 also receives input signalsfrom generator 254. The status information signals received byelectronic power governor 268 are input to gen set monitor 274 throughinterface module 276. In accordance with the particular power need andthe output of voltage regulator 266, gen set monitor 274 generatescontrol signals for return to electronic power governor 268 throughinterface module 276. In accordance with the particular control signals,electronic power governor 268 generates control signals input togenerator 254 to vary the output thereof. Electronic power governor 268also provides control signals to voltage regulator 266. In particular,electronic power governor can vary the engagement of generator 254 withoutput shaft 260 thereby varying the rotational speed of generator 254which in turn varies the voltage output to voltage regulator 266.

Gen set monitor 274 also provides control signals to electronic devicecontrol module (EDCM) 296. Electronic device control module 296 receivescontrol information from gen set monitor 274 regarding the poweravailability of the combined battery power source 246 and motorgenerator set 250. Electronic device control module 296 also receivesvariable battery voltages of 12 volts, 24 volts, and 36 volts resultingfrom selectively tapping specified battery combinations of battery powersource 246. Electronic device control module 296 selectively actuatescontactors 298 and 300 to provide power to drive control electricalenergy to drive motor 304 via drive control module 303. Electronicdevice control module 296 also selectively actuates contactors 302 and304 to operate reel motors 306 (only one of which is shown). Similarly,electronic device control module 296 selectively actuates contactors 308and 310 to operate headlights 312. In this manner, electronic devicecontrol module 296 selectively operates electric devices at various,predetermined voltages in accordance with the opening and closing of therespective contactors. An operator provides input to electronic devicecontrol module 296 via a plurality of switches and dials which comprisean operator control panel (OCP) 314. Thus, in accordance with operatorinput from operator control panel 314, the electronic device controlmodule 296 selectively activates the drive motor 304, the reel motor306, and the headlights 312. Further, drive control module 303 variesthe speed of the drive motor 304 via input from electronic devicecontrol module 296. In operation, the operator varies the position of afoot pedal which generates an input signal to electronic control module296. The electronic drive control module 296 outputs a control signal todrive control module 303 which modulates the electrical energy appliedto drive motor 304 to control the speed of drive motor 304 and,resultantly, the speed of the electrohydraulic mower 230.

The internal combustion motor 252 of motor generator set 250 alsoprovides mechanical input to a hydraulic pump in order to providepressure for a hydraulic control system to enable manipulation of therear wheels to steer the electrohydraulic mower 230 and to raise andlower the reel mowers. Internal combustion motor 252 causes rotation ofan output shaft 320 which causes rotation of an input shaft 322 via acoupling 324. Input shaft 322 provides rotational energy to the inputside of electromagnetic powered clutch (EMPC) 326. An output shaft 328of electromagnetic powered clutch 326 provides mechanical energy at theoutput of electromagnetic power clutch 326 to a variable volumedisplacement hydraulic pump 330. A hydraulic tank 332 stores hydraulicfluid input to the variable displacement hydraulic pump 330 through afilter 334 and an air to oil heat exchanger 336. Output pressure fromvariable displacement hydraulic pump 330 actuates a pressure switch 338.When the pressure within the hydraulic system drops below apredetermined threshold, the pressure switch 338 engages theelectromagnetic powered clutch 326, thereby mechanically coupling theinput shaft 322 and output shaft 328. This results in an increase in thehydraulic fluid pressure output from variable displacement hydraulicpump 330. Pressure in the hydraulic system is transferred throughrelatively rigid hydraulic tubing 340 and flexible hydraulic hose 342.The hydraulic hose 342 is generally a flexible hose which providesdampening of hydraulic noise resulting from the operation of thevariable displacement hydraulic pump 330. An air-over-oil accumulator342 provides a pressure reserve to compensate for pressure dropsoccurring upon actuation of variable displacement hydraulic pump 330.

The hydraulic fluid pressure is input to directional control valve (DCV)346. The directional control valve 346 includes a pair of solenoids 348and 350. Modulation of solenoid 348 results in hydraulic fluid flowthrough hydraulic control lines 356a and flexible hydraulic hose 352.Modulation of solenoid 348 results in the introduction of hydraulicfluid pressure into a first portion 354 of hydraulic fluid chamber 362.Actuation of solenoid 350 results in hydraulic fluid flow throughhydraulic control lines 356b and flexible hydraulic hose 358 to enableintroduction of hydraulic fluid pressure to a second portion 360 of thehydraulic fluid chamber 362. Operation of a switch pack on operatorcontrol panel 314 results in the selective actuation of solenoids 348and 350. This selective actuation in turn enables fluid flow into afirst portion 354 or second portion 360 of a hydraulic fluid chamber362. The hydraulic fluid chamber 362 is fixed at one end 364 andincludes a piston 366 separating the first portion 354 from the secondportion 360 of the hydraulic fluid chamber 362. The piston connects toan output shaft 368. The output shaft connects to a reel lift lever 370which is anchored at one end to a portion of the frame 232. Introductionof hydraulic fluid at pressure into one of the first or second portionof the hydraulic fluid chamber 362 results in a pressure imbalancethereby displacing the piston 366 and attached output shaft 368 withinthe fixed hydraulic fluid chamber 362. This displacement results in theraising and lowering of reel lift motor 372. Directional control valve346 also includes an overflow line 374 for returning hydraulic fluid tohydraulic tank 332.

Fluid under pressure is also applied to a proportional control valve 380which enables fluid flow through hydraulic lines and hoses 382, 384, and386, 388, respectively. In accordance with rotation of steering wheel391, fluid flow through proportional control valve 380 varies, therebyresulting in a variation in the hydraulic pressure applied to a firstportion 390 or a second portion 392 of a hydraulic fluid chamber 394.The hydraulic chamber is fixed at at least one end 396 so that thepressure differential between the first portion 390 and a second portion392 of hydraulic fluid chamber 394 results in displacement of piston rod398. Displacement of piston rod 398 results in displacement of steeringlever 400 which is fixed at one end 402 to the frame 232. Displacementof the piston rod 398 results in rotation of the steerable rear wheels236 to effect steering of electrohydraulic mower 230.

Another particularly advantageous feature of this invention is theincorporation of various forms of sound abatement to significantlyreduce the exterior noise levels generated by the electrohydraulic mower230. Internal combustion motor 252 outputs exhaust through a mufflersystem 410 which is housed in a baffled enclosure 412 which includessound abatement material 414 formed in a series of baffles whichsignificantly reduces the sound output to the exterior of the housing256. The material defining the baffles is preferably a refractory typematerial which is significantly resistive to the combustion byproductgases typically emitted from an internal combustion motor. On theinterior, the housing preferably includes a secondary sound abatementmaterial 420 many of which are known in the art. The secondary soundabatement material 420 lines the interior of the sound abatementmaterial 414 thereby providing an additional level of sound abatement.Optionally, the housing 256 may also include various forms of soundabatement material, many of which are well known in the art. Furtheryet, the housing 256 and the sound abatement material 414 and 420 alsopreferably includes an opening 422 to enable an input airflow to provideadequate temperature control. The housing 256 and sound abatementmaterial 414 and 420 also preferably includes an exit passage 444 toassist in the free flow of air through housing 256, thereby maintainingan adequate operating temperature within the housing 256.

With regard to each of the above discussed mowers, there may be somesituations in which it is desirable to provide a riding mower in which amotor generator set provides electrical energy for driving anelectrically driven hydraulic pump motor which in turn drives ahydraulic pump to provide hydraulic fluid pressure. The hydraulic fluidpressure could operate the primary mover, the reel mower motors, thelift motors, and the rear wheel steering mechanism. Such a configurationsignificantly reduces the requirement for electric storage batteries toa starting battery to start the motor generator set. FIG. 7 depicts anelectrohydraulic system 450 in which a motor generator set provideselectrical energy to drive an electrically driven hydraulic pump motor.An internal combustion motor 452 outputs mechanical energy in the formof rotation of output shaft 454 to provide mechanical input to generator456. Mechanical energy applied to generator 456 results in the output ofelectrical energy which is input to voltage regulator 458. The voltageregulator 458 in turn outputs a regulated voltage for driving theelectronic components of the electrohydraulic system 450. In particular,voltage regulator 458 outputs a voltage applied to hydraulic pump motor460. Hydraulic pump motor 460 is an electrically driven motor having anoutput shaft 462 for driving hydraulic pump 464. Hydraulic pump 464generates a hydraulic fluid pressure which may be applied to thehydraulically actuated devices. Examples of such devices may be foundwith reference to the reel motors, the lift motors, the primary mover,and the steering mechanism.

In operation, a pump motor controller 466 modulates the electricalenergy applied to hydraulic pump motor 460, thereby varying the speed ofhydraulic pump motor 460 and the resultant output pressure generated byhydraulic pump 464. The hydraulic pump 464 receives hydraulic fluidstored in a hydraulic tank 468 which passes through a hydraulic heatexchanger 469 to cool the hydraulic fluid before introduction tohydraulic pump 464. Transfer of hydraulic fluid between hydraulic heatexchanger 469 and hydraulic pump 464 occurs through hydraulic hose 470.As described above, use of flexible hydraulic hose significantly reducesnoise introduced in the system due to the operation of hydraulic pump464. Hydraulic pump 464 outputs hydraulic fluid at a pressure topressure switch 472 via pressure relief valve 474. Pressure relief valve474 bleeds off fluid back to hydraulic tank 468 when hydraulic pressureexceeds a predetermined threshold to prevent an over-pressure conditionin the hydraulic system. Pressure switch 472 provides feedback controlto pressure motor controller 466 to actuate hydraulic pump motor 460 inorder to maintain pressure at a predetermined level. An air over oilaccumulator 476 stores reserve hydraulic pressure to compensate forpressure drops due to actuation of the hydraulic pump 464. Hydraulicfluid at pressure output from accumulator 476 is then input to thevarious hydraulically driven devices.

The hydraulic pump 464 and hydraulic pump motor 460 are preferablyhoused within an insulated compartment having a sound attenuatinghousing 478 to reduce external noise in the system, thereby furtherquieting the mower. The sound attenuating housing 478 preferablyincludes a ventilation panel 480 located at both ends of the soundattenuating housing 478 in order to provide ventilation to reduceoperating temperatures of the hydraulic pump motor 460, the hydraulicpump 464, and associated components. To provide cooling of the motorgenerator set, the electrohydraulic system 450 also includes a fan motorcontroller 482 which receives input from a temperature sensor 484mounted in proximity to voltage regulator 458. Temperature sensor 484outputs a temperature signal to fan motor controller 482 varying inaccordance with the temperature in proximity to voltage regulator 458.When the temperature in the proximity of the voltage regulator 458reaches a predetermined threshold, fan motor controller 482 actuates fanmotor 486. Fan motor 486 drives an output shaft 488 and resultantlycauses rotation of cooling fan 490 in order to ventilate the housing 492of the electrohydraulic system 450. The housing 492 also includesventilation panels 495 at both ends in order to provide an airflow pathso that warm air may be exhausted from the interior of the housing andcool air brought into the interior of the housing.

A particularly advantageous feature of the embodiment of FIG. 7 is theintroduction of both passive and active sound abatement. Regardingpassive sound abatement, housing 492 is preferably formed of soundattenuating metallic material which provides both sound abatement and aprotective outer shell for the interior components. Mounted to theinterior of housing 492 is an additional layer of sound attenuatingmaterial 496. This sound attenuating material 496 preferably is aresilient material, such as glass-reinforced closed cell urethane sheet.As a further form of passive sound abatement, internal combustion motor452 outputs exhaust through a pair of mufflers 500 which partiallyattenuate the sound produced by internal combustion motor 452.

The present embodiment also discloses a second type of noisecancellation, namely, active noise cancellation. The active noticecancellation system includes one or a plurality of microphones 502 whichprovide an input signal to active noise cancellation controller 504.Active noise cancellation controller 504 analyses the signal input fromeach microphone and generates a negative signal 180 degrees out-of-phasewith the received input signal. The active noise cancellation controlleroutputs the negative signal to the output speaker 506 corresponding tothe microphone which generated that particular signal. The outputspeakers 506 thus generates an audio output corresponding to thenegative of the audio signal detected by the associated microphones 502.This cancels the noise in that particular vicinity. Thus, the presentsystem further reduces the external sound generated by the turf mower.

FIG. 8 depicts a second embodiment of a hydraulic drive system 520 ofthe present invention in which an internal combustion motor drives thehydraulic pump directly. Note that like referenced numerals will be usedto refer to similar elements described in FIG. 7, which operatessimilarly and will be described only minimally. An internal combustionmotor 452 operates to cause rotation of an output shaft 454 which iscoupled with hydraulic pump 464. Rotation of hydraulic pump 464pressurizes fluid received from hydraulic tank 468 via hydraulic hose470. Hydraulic pump 464 outputs hydraulic fluid at a pressure viahydraulic hose 470 and tubing 522 to hydraulic valve stock 524 andhydraulic operator controls 526. By manipulation of hydraulic operatorcontrols 526, which include individual controls 528, 530, and 532, theoperator may engage hydrostatic transmission 534. Hydrostatictransmission 534 provides mechanical energy for turning drive wheels536. Note that through operation of the selected individual controls528, 530, and 532, the drive wheels 536 may be operated independently soas to provide a drive wheel steering capability to the turf mower.Hydraulic pump 464 also includes an output shaft 540 which providesmechanical input to alternator 542. Alternator 542 outputs voltage tovoltage regulator 546. The output for voltage regulator 546 is in turninput to battery 548 and provides a charging energy to battery 548.

Temperature control of the interior of the housing 492 is provided bymeans of airflow through ventilation panels 495 which include a seriesof vent ports to enable the exhaust of warm air and the introduction ofcooler air to cool the housing. To further augment cooling, a fan motorcontroller 482 monitors two temperature sensors, a first temperaturesensor 547 is placed in proximity to internal combustion motor 452, anda second temperature sensor 549 is placed in proximity to hydraulic pump464. Fan motor controller 482 monitors the input signal received fromeach of the respective temperature sensors 547 and 549. When thetemperature indicated by either of the sensors exceeds a predeterminedthreshold, fan motor controller 482 actuates fan motor 486 to causerotation of cooling fan 490. Cooling fan 490 provides an airflow overhydraulic heat exchanger 469 and other components within the housing492.

In the present embodiment, noise cancellation occurs similarly asdescribed with respect to FIG. 7, including both passive and activenoise cancellation. Regarding passive noise cancellation, soundattenuating housing 492 includes a sound attenuating metallic material494 defining the exterior of the sound attenuating housing 492. Thesound attenuating metallic material 494, a resilient sound attenuatingmaterial 496 is mounted interiorly to the exterior sound attenuatingmetallic material 494. Further, the present embodiment also includesactive noise cancellation which operates as described above with respectto FIG. 8.

In yet an additional embodiment, the present invention also contemplatesa fly by wire system in which a microprocessor receives operator controlinputs and generates control outputs to effect steering and driveoperations of the electric mower. FIG. 9 depicts a block diagram of suchan embodiment. A microcomputer 550 includes a microprocessor (MP), aclock or time base (TB), such as a controlled crystal oscillator, arandom access memory (RAM), and a read only memory (ROM). The elementsof the microcomputer communicate via a bus 552 which enables thetransfer of data between each of the above described elements.Microcomputer 550 also includes various input and output ports andadapters. For example, microcomputer 550 includes input/output portsIO1, IO2, IO3, and IO4 for enabling the input and output of digitalsignals. Microcomputer 550 also includes an analog-to-digital converter(ADC1) for the conversion of input signals from analog to digital formatand a digital-to-analog converter (DAC2) for the conversion of digitalto analog signals for output. Programming and control information may bestored in electrical erasable programmable read only memory (EEPROM)which communicates with microcomputer 550 via input/output port IO4. TheEEPROM is configured as a read only memory which may be rewritten inaccordance with electrical inputs. Thus, the EEPROM is particularlyuseful for storing various control and calibration parameters which mayvary in accordance with the particular function and configuration of themower on which the system of FIG. 9 is installed. Similarly, additionalinput and output information (such as for diagnostics) may becommunicated with microcomputer 550 via serial communications interface(SCOMM) which also communicates with microcomputer 550 via input/outputport IO4. Each of the input/output ports communicates with the otherelements of microcomputer 550 via bus 552.

In operation, microcomputer 550 effectuates fly-by-wire operation ofseveral different systems of the electric mower, such as raising andlowering and engagement and disengagement of the reel mowers, speedcontrol, steering control, and various other functions. Regarding speedcontrol, microcomputer 550 receives inputs related to speed control fromthe drive pedal 552, the brake pedal 560, and the drive motor 568.Microcomputer 550 determines the operator desired speed of the electricmower in accordance with the position drive pedal 552. Depressing drivepedal 552 against the biasing force supplied of spring 554, which isseated on a fixed spring seat 556, causes rotation of potentiometer 558.Varying the position of potentiometer 558 generates a speed commandsignal (SCS) which is input to microcomputer 550 through input/outputport IO3. The speed command signal is multiplexed through an analogmultiplexer (AMUX) which receives control signals then input to portsIO3 and ADC1. Microcomputer 550 similarly determines the position ofbrake pedal 560. When the operator depresses brake pedal 560, meshingengagement of a tooth gear or sprocket 562 causes rotation ofpotentiometer 564. Rotation of potentiometer 564 results in acorresponding variation in the brake pedal signal (BRPS) which is alsoinput to microcomputer 550 through the AMUX and one of input/output portIO3 or ADC1. Based on the position of the drive pedal 552 and brakepedal 560 which generate an SCS and BRPS signal, respectively,microcomputer 550 determines the speed of the electric mower desired bythe operator. In accordance therewith, microcomputer 550 determines thespeed of the mower and the current output of the drive motor 568 andproduces one or a plurality of control signals output to drive controlmodule 566. Such signals include a digital signal provided frominput/output port IO2 and an analog signal from digital-to-analogconverter DAC2. In accordance with the control signals, the drivecontrol module 566 modulates the output voltage to drive motor 568. Inaddition to the above-discussed low level control signals, drive controlmodule 566 is also biased with a 48 volt DC signal which provides thedriving energy to drive motor 568. Drive control module 566 alsoprovides additional feedback information to microcomputer 550 viainput/output port IO2, and such information may indicate the presentstatus and diagnostic information for drive motor 568 and drive controlmodule 566.

The present embodiment also incorporates fly-by-wire steering in whichelectrical signals generated by manipulation of a steering wheel 570 areinput to microcomputer 550 to generate control signals for operating asteering motor 588 to cause a corresponding adjustment of the steerablerear wheel 600 in accordance with the present position and the desiredsteering angle. In particular, an operator manipulates the steeringwheel 570 in accordance with a conventional steering apparatus to causerotation of shaft 572. A shaft position encoder 574 mechanicallycommunicates with the shaft 572 and generates position signals input tomicrocomputer 550 through input/output port IO1. In a first embodiment,the shaft 572 causes displacement of a potentiometer 576 which causes aresultant output signal input to microcomputer 550 through analogmultiplexer (AMUX). In a second embodiment, referring to block 575 shownin phantom, a shaft position encoder 574 provides steering wheelposition information to microcomputer 550. The shaft position encoder574 includes a pair of light emitting diodes (LEDs) 578a and 578b. TheLEDs 578a and 578b provide a light source directed through holes formedin a disc 580 attached to shaft 572. Rotation of shaft 572 provides acorresponding rotation of disc 580. Rotation of disc 580 blocks thelight paths between LEDs 578a and 578b and photodetectors 582a and 582b,respectively. Photodetectors 582a and 582b provide output signals toquadriture detector 584. Quadriture detector 584 determines thedisplacement and direction of rotation of steering wheel 570 inaccordance with the sequence of rising and falling pulses provided byphotodetectors 582a and 582b. Such shaft position encoding is well knownto one skilled in the art. Quadriture detector 584 provides an inputsignal to microcomputer 550 through input/output port IO1. Microcomputer550 in accordance with the signal provided by quadriture detector 584generates output signals in accordance with the rotational displacementand direction of steering wheel 570. The output signals generated bymicrocomputer 550 provides control information to steering motorcontroller 586. Steering motor controller 586 generates the appropriatecontrol signals to direct the rotation of steering motor 588. Steeringmotor 588 includes an output shaft 590 which provides mechanical inputto gear reducer 592. Gear reducer 592 generates rotational motion of anoutput shaft 594, at the end of which is attached a tooth gear 596.Tooth gear 596 engages a corresponding set of teeth on a sprocket 598.Thus, actuation of steering motor 588 results in rotational movement ofsprocket 598 which is in turn attached to steerable rear wheel 600.Steering motor 588 may preferably be a servo motor or any otherby-directional motor, may of which are well known to one skilled in theart. A 24 volt signal applied to steering motor controller 586 providesthe electrical driving energy for steering motor 588.

The present embodiment also includes fly-by-wire control of the raisingand lowering and the engagement of the reel motors. In particular, anoperator control panel 602 includes a trio of switches 604a, 604b, and604c. Switches 604a, 604b, and 604c control the raising and lowering ofthe left, middle, and rear mowers, respectively, as is found in atriplex mower configuration. Operator control panel 602 also includes arun switch 606 which enables operation of the reel mowers in the runposition and disables operation of the reel mowers in the off position.Operator control panel 602 also includes a lift control switch 606 forraising and lowering the reel mowers in accordance with the position ofthe switch 606. The output from operator control panel 602 is input tomicrocomputer 550 at input/output port IO1. Depending upon the positionof the respective switches, microcomputer 550 generates the appropriateoutput signal to operate the respective mowers.

The fly-by-wire system of FIG. 9 also provides input to microcomputer550 indicating the rotational speed of the respective reel mowers andthe ground speed. For example, reel mower 607 rotatably displaces theoutput shaft 608 resulting in a corresponding rotation of toothed wheel610. As the teeth of toothed wheel 610 pass tachometer pickup 612,tachometer pickup 612 outputs a frequency signal varying in accordancewith the rotational speed of output shaft 608. Similarly, a toothed withthe ground s in accordance with the ground speed of the electric mower.As the teeth of wheel 614 pass tachometer pickup 616, tachometer pickup616 outputs a frequency signal varying in accordance with the rotationalspeed of toothed wheel 614. Each of the frequency signals output bytachometer pickups 612 and 616 are input to digital to analog (DAC)converters 618 and 620, respectively. The digital to analog converters618 and 620 convert the digital frequency signal to an analog signalwhose value varies in accordance with the frequency of the digital inputsignal. DACs 618 and 620 output an analog signal to analog multiplexer(AMUX) which is in turn input to microcomputer 550 throughanalog-to-digital converter (ADC1) or input/output port IO3. Of course,it will be understood by one skilled in the art that the frequencysignals output by tachometer pickups 612 and 616 may be input directlyto a digital input of microcomputer 550 which could then directlydetermine the frequency of the input signal in order to obtain therotational speed of the reel to yield the vehicle speed. Further, itwill be understood by one skilled in the art that microcomputer 550 mayperform several functions incorporating the reel speed and mower speedinformation, including varying the output speed signals for operatingthe drive control module 566 and the reel speed.

A further feature of the embodiment of FIG. 9 involves implementing anoperator information center to provide the operator with pertinentcontrol information. For example, the fuel tank 624 includes a fuelsensor 626 which outputs a fuel level signal to analog multiplexer(AMUX) which is input to microcomputer 550 through input/output portIO3. Fuel sensor 626 may be any of a number of fuel sensors known in theart. Similarly, battery voltage levels of, for example, the six systembatteries may be input into analog multiplexer AMUX as signals B1V, B2V,B3V, B4V, B5V, and B6V. The battery voltage analog signal are tomicrocomputer 550 though analog-to-digital convertor ADC1 orinput/output port IO3. In response to these signals, microcomputer 550provides mower information embodied as signals output throughinput/output port IO2 to display driver 628. Display driver 628generates the appropriate control signals to operate LED display 630. Inthis manner, the LED display 630 provides the operator with pertinentcontrol information.

Microcomputer 550 further may operate a pair of solenoids SOL1 and SOL2through a pair of amplifiers 640 and 642, respectively. Solenoids SOL1and SOL2 are operable to control any of a plurality of possiblefunctions of an electric riding mower. Further yet, microcomputer 550may actuate pilot light PL by generating a control signal frominput/output port IO2. The signal generated from input/output port IO2is set to amplifier 646 and selectively actuates pilot light PL.

The foregoing detailed description shows that the preferred embodimentsof the present invention are well suited to fulfill the objectsabove-stated. It is recognized that those skilled in the art may makevarious modifications or additions to the preferred embodiments chosento illustrate the present invention without departing from the spiritand proper scope of the invention. For example, drive motors, reelmotors, lift motors and steering motors of different voltages may beutilized, and the taps into the battery packs may be changedaccordingly. Further, gear boxes may be used between the reels and reelmotors if desired, and the number of batteries in the battery pack maybe varied as needed.

While the present invention has been discussed with respect to ridingmowers having reel-type mowing heads, those skilled in the art willappreciate that it may be applied to electrically-powered riding mowershaving multiple rotary mowing heads. In addition, the electrical controlsystems, generator set arrangements, and virtually all other aspects ofthe present invention may be used in connection with other turf careequipment used to tend large expanses of grass. For example,electrically-powered riding sprayers, aerators, dethatchers, and otherequipment which would be beneficially operated in a pollution-free waywith extremely low noise would benefit by the systems and structures ofthe present invention. In other words, except for the working tool beinga mowing head, most such equipment can be readily adapted to utilize thevarious aspects of the present invention. Thus, the term "turf caremachine" or "turf care equipment" if used in the claims below is to beunderstood to extend to all such forms of power-consuming equipment whenarranged to be operated and/or driven using electrical motors and/orelectrically-powered work-producing devices. Accordingly, it is to beunderstood that the protection sought and to be afforded hereby shouldbe deemed to extend to the subject matter as defined by the appendedclaims, including all fair equivalents thereof.

We claim:
 1. A self-propelled riding mower comprising:a frame; aplurality of ground engaging wheels supporting the frame; means formechanically generating electrical energy supported from the frame; anda plurality of reel type lawn mowers supported from the frame and one ofthe plurality of reel type lawn mowers located forward of each of theplurality of ground engaging wheels, the reel type lawn mowers beingmoveable between a raised non-operative position and a lowered operativeposition in which the reel type lawn mowers engage the ground, each reelmower being driven by a respective electric motor which receiveselectrical power from the means for generating electrical energy.
 2. Theself propelled riding mower as defined in claim 1 further comprising aprime mover comprising an electric motor supplied with electrical energyfrom the means for generating electrical energy and adapted to providedriving torque to at least one of the ground engaging wheels.
 3. Theself-propelled riding mower of claim 1 wherein the means for generatingelectrical energy comprises a motor generator set.
 4. The self-propelledriding mower of claim 1 wherein the means for mechanically generatingelectrical energy further comprises:an internal combustion motor; and ameans for generating electrical energy in response to mechanical motion,the internal combustion motor operatively connected to the generatingmeans to impart the mechanical motion required to generate electricalenergy.
 5. The self propelled riding mower as defined in claim 4 furthercomprising a regulator circuit for modulating the electrical output ofthe means for generating electrical energy.
 6. The self-propelled ridingmower of claim 5 wherein the means for mechanically generatingelectrical energy further comprises a circuit for monitoring theelectrical output of the generator means and the electrical output ofthe regulator circuit, the circuit disabling the means for generatingelectrical energy from outputting electrical energy when the circuitdetects a non-standard electrical energy output condition.
 7. Theself-propelled riding mower of claim 1 further comprising a source ofstored electrical energy, the source of stored electrical energyproviding electrical energy in addition to the electrical energy outputby the means for generating electrical energy.
 8. The self-propelledriding mower of claim 1 further having a hydraulic fluid systemcomprising:hydraulic fluid stored in a reservoir; hydraulic pressuregenerating means for receiving hydraulic fluid from the reservoir at aninput pressure and providing hydraulic fluid at an output pressure; anda hydraulically actuated device responsive to the application ofhydraulic fluid pressure provided by the hydraulic pressure generatingmeans.
 9. The self-propelled riding mower of claim 8 further comprisingan electric motor operatively connected to and driving the hydraulicpressure generating means, the electric motor receiving electricalenergy from the means for generating electrical energy to operate theelectric motor.
 10. The self-propelled riding mower of claim 9 furthercomprising a clutch interconnecting the electric motor and the hydraulicpressure generating means in order to vary the force transferred betweenthe electric motor and hydraulic pressure generating means.
 11. Theself-propelled riding mower of claim 8 further comprising a source ofstored electrical energy, the source of stored electrical energy alsoproviding electrical energy in addition to the electrical energy outputby the means for generating electrical energy.
 12. The self propelledriding mower as defined in claim 11 further comprising an electric motordriving the hydraulic pressure generating means, where electrical energyoutput by the means for storing electrical energy is applied to theelectric motor to operate the pressure generating means.
 13. Theself-propelled riding mower of claim 12 further comprising a clutchinterconnecting the electric motor and the hydraulic pressure generatingmeans in order to vary the force applied to the electric motor to thehydraulic pressure generating means.
 14. The self-propelled riding mowerof claim 8 wherein the means for mechanically generating electricalenergy further comprises:an internal combustion motor; and a means forgenerating electrical energy in response to mechanical motion, theinternal combustion motor operatively connected to the generating meansto impart the mechanical motion required to generate electrical energy.15. The self-propelled riding mower of claim 14 wherein the internalcombustion motor mechanically powers the source of hydraulic fluidpressure.
 16. The self-propelled riding mower of claim 14 furthercomprising a clutch interconnecting the hydraulic pressure generatingmeans and the internal combustion motor in order to vary the forcetransferred between the internal combustion motor and hydraulic pressuregenerating means.
 17. The self-propelled riding mower of claim 8 whereinthere are at least three ground engaging wheels and wherein the primemover further comprises a drive axle positioned between two of thewheels for delivering driving torque to each of the two wheels andwherein the third wheel is located rearward of the drive axle and may berotatably displaced to steer the turf mower.
 18. The self-propelledriding mower of claim 17 further comprising a hydraulic pistonresponsive to hydraulic fluid pressure provided by the hydraulicpressure generating means and operatively connected to the third wheelso that extension of the hydraulic piston rotatably displaces the thirdwheel in a first direction and retraction of the hydraulic pistonrotatably displaces the third wheel in an opposite direction to steerthe turf mower.
 19. A self-propelled riding mower comprising:a frame; aplurality of ground engaging wheels supporting the frame; an internalcombustion motor supported from the frame; a means for generatingelectrical energy in response to mechanical motion, the internalcombustion motor operatively connected to the generating means to impartthe mechanical motion required to generate electrical energy; aplurality of reel type lawn mowers supported from the frame and one ofthe plurality of reel type lawn mowers located forward of each of theplurality of ground engaging wheels, each reel mower being driven by arespective electric motor which receives electrical power from the meansfor generating electrical energy; and a prime mover adapted to providedriving torque to at least one of the ground engaging wheels, the primemover comprising an electric motor supplied with electrical energy fromthe means for generating electrical energy.
 20. The self propelledriding mower as defined in claim 19 wherein the means for generatingelectrical energy outputs a direct current electrical signal, and theprime mover is an electric motor powered by a direct current electricalsignal.
 21. The self propelled riding mower as defined in claim 19wherein the means for generating electrical energy outputs analternating current electrical signal, and the prime mover is anelectric motor powered by an alternating current electrical signal. 22.The self propelled riding mower as defined in claim 19 furthercomprising a voltage regulator for monitoring the voltage output by themeans for generating electrical energy, the voltage regulator modulatingthe voltage output by the means for generating electrical energy andsupplying a regulated voltage for use by the electrical components ofthe mower.
 23. The self propelled riding mower as defined in claim 19wherein the means for generating electrical energy outputs analternating current electrical signal, and the prime mover is anelectric motor powered by a direct current electrical signal, and themower further comprises a means for transforming the alternating currentelectrical signal into a direct current electrical signal forapplication to the electric motor.
 24. The self-propelled riding moweras defined in claim 23 further comprising a source of stored electricalenergy, the source of stored electrical energy providing electricalenergy to the electric motor in addition to the means for generatingelectrical energy.
 25. The self-propelled riding mower as defined inclaim 23 further comprising a motor controller for modulating theelectrical energy applied to the prime mover, thereby varying the outputof the prime mover in accordance with the modulated energy applied tothe prime mover.
 26. The self propelled riding mower as defined in claim19 wherein the means for generating electrical energy outputs a directcurrent electrical signal, and the prime mover is an electric motorpowered by a direct current electrical signal, and the mower furthercomprises a means for modulating the electrical output of the means forgenerating electrical energy for application to the electric motor. 27.The self-propelled riding mower as defined in claim 26 furthercomprising a source of stored electrical energy, the source of storedelectrical energy providing electrical energy to the electric motor inaddition to the means for generating electrical energy.
 28. Theself-propelled riding mower as defined in claim 26 further comprising amotor controller for modulating the electrical energy applied to theprime mover, thereby varying the output of the prime mover in accordancewith the modulated energy applied to the prime mover.
 29. The selfpropelled riding mower as defined in claim 19 wherein the means forgenerating electrical energy outputs an alternating current electricalsignal, and the prime mover is an electric motor powered by analternating current electrical signal, and the mower further comprises ameans for modulating the electrical output of the means for generatingelectrical energy for application to the electric motor.
 30. Theself-propelled riding mower as defined in claim 29 further comprising asource of stored electrical energy, the source of stored electricalenergy providing electrical energy to the electrical motor in additionto the means for generating electrical energy.
 31. The self-propelledriding mower as defined in claim 29 further comprising a motorcontroller for modulating the electrical energy applied to the primemover, thereby regulating the output of the prime mover in accordancewith the modulated energy applied to the prime mover.
 32. The selfpropelled riding mower as defined in claim 19 wherein the means forgenerating electrical energy outputs a direct current electrical signal,and the prime mover is an electric motor powered by an alternatingcurrent electrical signal, and the mower further comprises a means formodulating the electrical output of the means for generating electricalenergy for application to the electric motor.
 33. The self-propelledriding mower as defined in claim 32 further comprising a source ofstored electrical energy, the source of stored electrical energyproviding electrical energy to the electric motor in addition to themeans for generating electrical energy.
 34. The self-propelled ridingmower as defined in claim 32 further comprising an inverter fortransforming the direct current signal output by the means forgenerating electrical energy to an alternating current electrical signalfor application to the prime mover, and further regulating the output ofthe prime mover in accordance with varying the input voltage applied tothe prime mover.
 35. The self propelled riding mower as defined in claim19 further comprising a motor controller for modulating the electricalenergy applied to the prime mover, thereby regulating the output of theelectric motor in accordance with the modulated energy applied to theprime mover.
 36. The self-propelled riding mower as defined in claim 19further comprising an electronic control module for receiving operatorinput to direct operation of the prime mover and for generating controlsignal to at least one of a voltage regulator or a motor controller. 37.The self-propelled riding mower as defined in claim 36 wherein theoperator inputs include at least one of a drive pedal signal, a brakepedal signal, and operator mower request signal.
 38. The self-propelledriding mower as defined in claim 36 wherein the electronic controlcircuit further comprises a reel motor controller and a lift motorcontroller corresponding to each of the respective reel motors and liftmotors.
 39. A self-propelled riding mower comprising:a frame; aplurality of ground engaging wheels supporting the frame; means formechanically generating electrical energy; hydraulic pressure generatingmeans for receiving hydraulic fluid at an input pressure and providinghydraulic fluid at an output pressure; drive means powered by electricalenergy produced by the means for generating electrical energy, the drivemeans providing mechanical drive to the hydraulic pressure generatingmeans to enable the output of hydraulic fluid at the output pressure;and a plurality of reel type lawn mowers supported from the frame andone of the plurality of reel type lawn mowers located forward of each ofthe plurality of ground engaging wheels, the reel type lawn mowers beingmoveable between a raised non-operative position and a lowered operativeposition in which the reel type lawn mowers engage the ground, each reelmower being driven by a respective electric motor which receiveselectrical power from the means for generating electrical energy. 40.The self propelled riding mower as defined in claim 39 wherein the drivemeans further comprises an electric motor.
 41. The self-propelled ridingmower as defined in claim 39 further comprising a pump motor controllerfor modulating the electrical energy applied to the drive means tomodulate the electrical energy applied to the drive means, therebyvarying the hydraulic fluid output pressure in accordance with themodulated electrical energy.
 42. The self-propelled riding mower asdefined in claim 39 further comprising a voltage regulator receiving asinput electrical energy from the means for mechanically generatingelectrical energy and providing an output electrical energy within apredetermined range.